Neuroprotection in oxidative stress-related neurodegenerative diseases: role of endocannabinoid system modulation.

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“Redox imbalance may lead to overproduction of reactive oxygen and nitrogen species (ROS/RNS) and subsequent oxidative tissue damage which is a critical event in the course of neurodegenerative diseases. It is still not fully elucidated, however, whether oxidative stress is the primary trigger or a consequence in process of neurodegeneration.

Recent Advances: Increasing evidence suggests that oxidative stress is involved in the propagation of neuronal injury and consequent inflammatory response, which in concert promote development of pathological alterations characteristic of most common neurodegenerative diseases.

Critical Issue: Accumulating recent evidence also suggests that there is an important interplay between the lipid endocannabinoid system (ECS; comprising of the main cannabinoid 1 and 2 receptors (CB1 and CB2), endocannabinoids and their synthetic and metabolizing enzymes) and various key inflammatory and redox-dependent processes.

FUTURE DIRECTIONS:

Targeting the ECS in order to modulate redox state-dependent cell death, and to decrease consequent or preceding inflammatory response holds therapeutic potential in multitude of oxidative stress-related acute or chronic neurodegenerative disorders from stroke and traumatic brain injury to Alzheimer`s and Parkinson`s diseases, and multiple sclerosis, just to name a few, which will be discussed in this overview.”

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Cannabidiol reduces lung injury induced by hypoxic-ischemic brain damage in newborn piglets.

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“Brain hypoxic-ischemic (HI) damage induces distant inflammatory lung damage in newborn pigs. We aimed to investigate the effects of cannabidiol (CBD) on lung damage in this scenario.

RESULTS:

CBD prevented HI-induced deleterious effects on TLC and OI and reduced lung histological damage, modulating inflammation (decreased leukocyte infiltration and IL-1 concentration) and reducing protein content in BALF and EVLW. These effects were related to CBD-induced anti-inflammatory changes in the brain. HI did not increase oxidative stress in the lungs. In the lungs, WAY100635 blunted CBD’s beneficial effects on histological damage, IL-1 concentration and EVLW.

CONCLUSIONS:

CBD reduced brain HI-induced distant lung damage, with 5-HT1A receptor involvement in these effects. Whether CBD’s effects on lungs were due to anti-inflammatory effects on the brain or to direct effects on lungs remains to be elucidated.” https://www.ncbi.nlm.nih.gov/pubmed/28388598

“Hypoxic-ischemic brain injury is a diagnostic term that encompasses a complex constellation of pathophysiological and molecular injuries to the brain induced by hypoxia, ischemia, cytotoxicity, or combinations of these conditions. The typical causes of hypoxic-ischemic brain injury – cardiac arrest, respiratory arrest, near-drowning, near-hanging, and other forms of incomplete suffocation, carbon monoxide and other poisonous gas exposures, and perinatal asphyxia – expose the entire brain to potentially injurious reductions of oxygen (i.e., hypoxia) and/or diminished blood supply (ischemia).”  http://www.internationalbrain.org/articles/hypoxicischemic-brain-injury/

“Hypoxic-ischemic brain damage induces distant inflammatory lung injury in newborn piglets.” https://www.ncbi.nlm.nih.gov/pubmed/25950454

“Cannabidiol reduces lung injury induced by hypoxic-ischemic brain damage in newborn piglets.” https://www.ncbi.nlm.nih.gov/pubmed/28388598

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Neuroprotective effect of WIN55,212-2 against 3-nitropropionic acid-induced toxicity in the rat brain: involvement of CB1 and NMDA receptors.

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“The endocannabinoid system (ECS), and agonists acting on cannabinoid receptors (CBr), are known to regulate several physiological events in the brain, including modulatory actions on excitatory events probably through N-methyl-D-aspartate receptor (NMDAr) activity.

Actually, CBr agonists can be neuroprotective.

Our results demonstrate a protective role of WIN55,212-2 on the 3-NP-induced striatal neurotoxicity that could be partially related to the ECS stimulation and induction of NMDAr hypofunction, representing an effective therapeutic strategy at the experimental level for further studies.”

https://www.ncbi.nlm.nih.gov/pubmed/28337258

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Cannabis Use Has Negligible Effects Following Severe Traumatic Injury.

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“Nearly half of all states have legalized medical marijuana or recreational-use marijuana. As more states move toward legalization, the effects on injured patients must be evaluated.

This study sought to determine effects of cannabis positivity at the time of severe injury on hospital outcomes compared with individuals negative for illicit substances and those who were users of other illicit substances.

Cannabis users suffering from severe injury demonstrated no detrimental outcomes in this study compared with nondrug users.”

https://www.ncbi.nlm.nih.gov/pubmed/28272189

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Cell-Autonomous Excitation of Midbrain Dopamine Neurons by Endocannabinoid-Dependent Lipid Signaling.

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“The major endocannabinoid in the mammalian brain is the bioactive lipid 2-arachidonoylglycerol (2-AG). The best-known effects of 2-AG are mediated by G-protein-coupled cannabinoid receptors. In principle, 2-AG could modify neuronal excitability by acting directly on ion channels, but such mechanisms are poorly understood.

Using a preparation of dissociated mouse midbrain dopamine neurons to isolate effects on intrinsic excitability, we found that 100 nM 2-AG accelerated pacemaking and steepened the frequency-current relationship for burst-like firing. In voltage-clamp experiments, 2-AG reduced A-type potassium current (IA) through a cannabinoid receptor-independent mechanism mimicked by arachidonic acid, which has no activity on cannabinoid receptors. Activation of orexin, neurotensin, and metabotropic glutamate Gq/11-linked receptors mimicked the effects of exogenous 2-AG and their actions were prevented by inhibiting the 2-AG-synthesizing enzyme diacylglycerol lipase α.

The results show that 2-AG and related lipid signaling molecules can directly tune neuronal excitability in a cell-autonomous manner by modulating IA.”

https://www.ncbi.nlm.nih.gov/pubmed/28262417

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Inflammatory Regulation by Driving Microglial M2 Polarization: Neuroprotective Effects of Cannabinoid Receptor-2 Activation in Intracerebral Hemorrhage.

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“The cannabinoid receptor-2 (CB2R) was initially thought to be the “peripheral cannabinoid receptor.” Recent studies, however, have documented CB2R expression in the brain in both glial and neuronal cells, and increasing evidence suggests an important role for CB2R in the central nervous system inflammatory response.

Intracerebral hemorrhage (ICH), which occurs when a diseased cerebral vessel ruptures, accounts for 10-15% of all strokes. Although surgical techniques have significantly advanced in the past two decades, ICH continues to have a high mortality rate.

The aim of this study was to investigate the therapeutic effects of CB2R stimulation in acute phase after experimental ICH in rats and its related mechanisms.

These findings demonstrated that CB2R stimulation significantly protected the brain damage and suppressed neuroinflammation by promoting the acquisition of microglial M2 phenotype in acute stage after ICH.

Taken together, this study provided mechanism insight into neuroprotective effects by CB2R stimulation after ICH.”

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Endocannabinoids: A Promising Impact for Traumatic Brain Injury.

 

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“The endogenous cannabinoid (endocannabinoid) system regulates a diverse array of physiological processes and unsurprisingly possesses considerable potential targets for the potential treatment of numerous disease states, including two receptors (i.e., CB1 and CB2 receptors) and enzymes regulating their endogenous ligands N-arachidonoylethanolamine (anandamide) and 2-arachidonyl glycerol (2-AG).

Increases in brain levels of endocannabinoids to pathogenic events suggest this system plays a role in compensatory repair mechanisms.

Traumatic brain injury (TBI) pathology remains mostly refractory to currently available drugs, perhaps due to its heterogeneous nature in etiology, clinical presentation, and severity. Here, we review pre-clinical studies assessing the therapeutic potential of cannabinoids and manipulations of the endocannabinoid system to ameliorate TBI pathology.

Specifically, manipulations of endocannabinoid degradative enzymes (e.g., fatty acid amide hydrolase, monoacylglycerol lipase, and α/β-hydrolase domain-6), CB1and CB2 receptors, and their endogenous ligands have shown promise in modulating cellular and molecular hallmarks of TBI pathology such as; cell death, excitotoxicity, neuroinflammation, cerebrovascular breakdown, and cell structure and remodeling.

TBI-induced behavioral deficits, such as learning and memory, neurological motor impairments, post-traumatic convulsions or seizures, and anxiety also respond to manipulations of the endocannabinoid system.

As such, the endocannabinoid system possesses potential drugable receptor and enzyme targets for the treatment of diverse TBI pathology.

Yet, full characterization of TBI-induced changes in endocannabinoid ligands, enzymes, and receptor populations will be important to understand that role this system plays in TBI pathology.

Promising classes of compounds, such as the plant-derived phytocannabinoids, synthetic cannabinoids, and endocannabinoids, as well as their non-cannabinoid receptor targets, such as TRPV1 receptors, represent important areas of basic research and potential therapeutic interest to treat TBI.”

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Co-localization of the cannabinoid type 1 receptor with corticotropin-releasing factor-containing afferents in the noradrenergic nucleus locus coeruleus: implications for the cognitive limb of the stress response.

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“The noradrenergic system has been shown to play a key role in the regulation of stress responses, arousal, mood, and emotional states. Corticotropin-releasing factor (CRF) is a primary mediator of stress-induced activation of noradrenergic neurons in the nucleus locus coeruleus (LC).

The endocannabinoid (eCB) system also plays a key role in modulating stress responses, acting as an “anti-stress” neuro-mediator.

In the present study, we investigated the cellular sites for interactions between the cannabinoid receptor type 1 (CB1r) and CRF in the LC.

Taken together, these results indicate that the eCB system is poised to directly modulate stress-integrative heterogeneous CRF afferents in the LC, some of which arise from limbic sources.”

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CB2 cannabinoid receptors modulate HIF-1α and TIM-3 expression in a hypoxia-ischemia mouse model.

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“The role of CB2 cannabinoid receptors (CB2R) in global brain lesions induced by hypoxia-ischemia (HI) insult is still unresolved.

The aim of this study was to evaluate the involvement of CB2R in the behavioural and biochemical underpinnings related to brain damage induced by HI in adult mice, and the mechanisms involved.

Our results indicate that CB2R may have a crucial neuroprotective role following HI insult through the modulation of the inflammatory-related HIF-1α/TIM-3 signalling pathway in microglia.”

https://www.ncbi.nlm.nih.gov/pubmed/28253997

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Endocannabinoid 2-arachidonoylglycerol protects inflammatory insults from sulfur dioxide inhalation via cannabinoid receptors in the brain.

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“Sulfur dioxide (SO2) pollution in the atmospheric environment causes brain inflammatory insult and inflammatory-related microvasculature dysfunction. However, there are currently no effective medications targeting the harmful outcomes from chemical inhalation.

Endocannabinoids (eCBs) are involved in neuronal protection against inflammation-induced neuronal injury. The 2-arachidonoylglycerol (2-AG), the most abundant eCBs and a full agonist for cannabinoid receptors (CB1 and CB2), is also capable of suppressing proinflammatory stimuli and improving microvasculature dysfunction.

Here, we indicated that endogenous 2-AG protected against neuroinflammation in response to SO2 inhalation by inhibiting the activation of microglia and astrocytes and attenuating the overexpression of inflammatory cytokines, including tumor necrosis factor alpha (TNF-a), interleukin (IL)-1β, and inducible nitric oxide synthase (iNOS).

In addition, endogenous 2-AG prevented cerebral vasculature dysfunction following SO2 inhalation by inhibiting endothelin 1 (ET-1), vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1) expression, elevating endothelial nitric oxide synthase (eNOS) level, and restoring the imbalance between thromboxane A2 (TXA2) and prostaglandin I2 (PGI2).

In addition, the action of endogenous 2-AG on the suppression of inflammatory insult and inflammatory-related microvasculature dysfunction appeared to be mainly mediated by CB1 and CB2 receptors.

Our results provided a mechanistic basis for the development of new therapeutic approaches for protecting brain injuries from SO2 inhalation.”

https://www.ncbi.nlm.nih.gov/pubmed/28115138

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